Paper product and its manufacture



Patented Oct. 28,1930

ERNEST Eorxmson, or NEW YORK, 1v. Y.,

PATENT OFFICE ASSIGNOR TO THE MECHANICAL RUBBER COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO PAPER PRODUCT AND ITS MANUFACTURE llo Drawing. App1ication filed May 27,

This invention relates to the manufacture of paper and more particularly to the combination therewith of rubber by a procedure resembling top-sizing.

5 As heretofore practiced, top-sizing has been carried on by passing a web or sheet of paper through a bath of glue or the like and subsequently drying the same. Faper so sized is comparatively stiff, harsh, and only moder ately flexible, and its usefulness is limited,

without intention to limit more than is required by the prior art, the invention briefly stated consists in forming a web or sheet of paper pulp and partially drying it before running it through a bath of rubber latex and then completely drying. the treated Web or sheet.

The web or sheet may be madein any desired way and on any convenient machine, such as those used in the manufacture of paper at the present time. Any suitable paperpulp may be employed and it may or may not have added to it in the beater usual sizing ingredients and/or a small percentage of rubber in a dispersed condition, such for instance as rubber latex diluted to a low rubber content. If natural rubber latex is employed it will preferably contain a small quantity of a pre- The web or sheet which has been prepared from paper pulp as above described'is then, after being partially dried, passed through a bath of rubber latex whose rubber content may be varied from 4 to To obtain the required strength of thelatex bath, the latex may be either diluted concentrated or thickened in any convenient manner. If the proc ess is carried out on a standard type of paper servative such as ammonia or formaldehyde.

machine, either a Fourdrinier for paper 1924. Serial No. 716,163.

sheets or a cylinder machine for thick paper and boards, the web or sheet may be passed down from the drying drums intermediate the length of the battery thereof and into the bath of latex in an incompletely dry condi- 55 tion, then threaded through the second battery of drying drums so that thesizing treatment may be carried on continuously and substantially as heretofore practiced with other sizing solutions. In order to avoid an an excess of the rubber latex being carried up from the sizing bath and also to assist in working the latex into the body of the damp web or sheet of partially formed paper, squeeze rolls may be located above the bath 55 or both in and above the bath. The paper may be dried after sizing treatment with latex however festooned in drying lofts or otherwise as convenient instead of on dry cans. After drying the paper may be and is preferably calendered. v

The properties of the resulting paper will of course depend somewhatupon the properties of the original paper web which is subjected to the top-sizing process with latex. Tests have been carried out on various kinds of paper, viz: sulphite, ground wood, newsprint kraft, manila, rag (ledger), greaseproof, and glassine. In general it has been found that the latex top-sized paper posso sesses greatly increased folding strength. In some instances papers which have been top-sized with" 4-8% rubber latex have over Y 100% greater folding strength than the same paper without any sizing. material. The same is true of the bursting strength -of the paper as indicated by a Mullen test. In some cases increase in bursting strength as high as 25% greater than that of the original untreated paper have been obtained where comparatively low amounts of rubber have been retained by the paper.

Experiments have been carried out on the various kinds of papers mentioned above, namely, sulphite, ground wood news-print, kraft, manila, rag (ledger), grease-proof, and glassine, to, determinev what concentrationof rubber latex produces the best results. I The concentration varies with the kinds of paper treated, and the purpose for which it is 106 to be used. In general, however, it is noted that so far as increasing the bursting strength of ordinary paper is concerned, there is little to be gained by using a latex which contains more than 8% of rubber solsubstantial dryness.

It is to be understood, however, that the invention is not confined to using rubber latex small proportions as paper may be manufactured with a greater percentage of rubber in the "finished paper by either repeatedly passing the same through a dilute latex bath or by using rubber latex which has been thickened or concentrated above its natural strength which lies between 25-35%.

The invention'is moreover not confined to the use of rubber latex alone as combinations of the same with vulcanizing ingredients and/or any one or more sizing ingredients, such as water-glass, glue, borated shellac, and casein or other usual sizing ingredients may be employed. These may be mixed in with the rubber-latex or with artificially prepared latex in an manner convenient and in proportions whic may be left to the discre- 'derstood that I do not tion of the manufacturer in order to obtain desired characteristics.

As many apparently widely different embodiments of this invention may be made without departing from the spirit thereof,- in the apphcation of the size containing latex for instance sprayingon one or both sides paper which consists in maln'ng a web of paper pulp, partially drying the same,-filhng in surface irregularities by applying thereto a top size containing rubber latex and completel drying the web to form a sheet.

4. X process of manufacturing a rubberized paper which consists in continuously forming a web of paper pulp, applying thereto a top size containi rub er-latex of 48% solids content, an calendering the treated web to form a finished length of paper.

5. A paper top sized and superficially imregnated with rubber and having a velvety eel, high flexibility, and high resistance to folding, bursting and spreading of 6. A paper product formed by a papermaking process superficially impregnated and surfaced with size containing rubber.

7. A process of manufacturing a rubberized paper which consists in superficially applying size containing rubber latex to a moist sheet of paper pulp while moving, and thereafter sheet to form rubber sized pa er.

8. A paper impregnated ad acent its exterior surface only with the dried deposit from rubber latex.

Signed at New York, New York, this 13th day of May, 1924.

- ERNEST HQ'PKINSONJ being contemplated as an alternative to passwill be unintend to limit myself to the specific embodiment herein set forth, except as indicated in the appended claims.

ing the web through a bathit Having thus described my invention, what i I claim and desire to protect by LettersPatentis:

1. A rocess of manufacturing rubberized paper w ich consists in maln'ng a web of paper pulp, removing moisture therefrom, ap-

plyin thereto a top size containin displerse rubber, and drying the web to orm a s eet.

2. A rocess of manufacturing rubberized paper w ch consists in making a web of paper pulp, partially drying the same, top sizing s it by continuously passing the web through a sizing bath containing dispersed rubber, and completely drying the web to form a sheet of any desired length.

3. -A process of manufacturing rubberized drying and calendering the treated 

